Carbon-sensitive pedotransfer functions for plant available water

Authors: BAGNALL, DIANNA - Soil Health Institute; MORGAN, CHRISTINE - Soil Health Institute; COPE, MICHAEL - Soil Health Institute; BEAN, GREGORY - Soil Health Institute; CAPPELLAZZI, SHANNON - Soil Health Institute; GREUB, KELSEY - Soil Health Institute; LIPTZIN, DANIEL - Soil Health Institute; NORRIS, CHARLOTTE - Soil Health Institute; RIEKE, ELIZABETH - Soil Health Institute; TRACY, PAUL - Soil Health Institute; Ashworth, Amanda; Baumhardt, Roland - Louis; Dell, Curtis; Derner, Justin; Ducey, Thomas; Fortuna, Ann Marie; Kautz, Mark; Kitchen, Newell; Moore, Philip; Osborne, Shannon; Owens, Phillip; Sainju, Upendra; Sherrod, Lucretia; Watts, Dexter

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2022
Publication Date: 3/20/2022
Citation: Bagnall, D.K., Morgan, C., Cope, M., Bean, G.M., Cappellazzi, S., Greub, K., Liptzin, D., Norris, C.E., Rieke, E.L., Tracy, P.W., Ashworth, A.J., Baumhardt, R.L., Dell, C.J., Derner, J.D., Ducey, T.F., Fortuna, A., Kautz, M.A., Kitchen, N.R., Moore Jr., P.A., Osborne, S.L., Owens, P.R., Sainju, U.M., Sherrod, L.A., Watts, D.B., et al. 2022. Carbon-sensitive pedotransfer functions for plant available water. Soil Science Society of America Journal. 86(3):612-629. https://doi.org/10.1002/saj2.20395.
DOI: https://doi.org/10.1002/saj2.20395

Interpretive Summary: A critical function of healthy soil is the ability to capture, store, and release water while preventing erosion by water. Consequently, improving these soil functions is a goal of soil health management systems. Improving soil hydraulic function is a motivating factor for farmers to adopt soil health management practices and is of growing importance due to increased temperature and precipitation variability caused by climate change. To quantify the effect of soil health management practices on ecosystem services that flow from soil hydraulic functions, indicators of various aspects of soil water cycling, storage, and erosion risk are needed. Researchers set out to compare and recommend soil health indicators of improved soil plant available water on 124 locations across Canada, Mexico, and the United States. Because soil hydraulic function is strongly influenced by management and inherent site characteristics, such as inherent soil properties (e.g. clay content) and climate (e.g. mean annual temperature), Researchers also aimed to consider the relationship between the soil health indicators and site characteristics. This North American Project to Evaluate Soil Health Measurements suggests field capacity measured on intact cores was the best measure of soil water function, because it responded to management, is proximal to stakeholder values, and its response to management but is not influenced by inherent and climatic variables. Overall, these results provide insight into how management and environmental conditions drive plant available water for helping combat climate change and improve a soil's capacity to store water and improve food production. These results are important for teasing apart how management drives soil health and affects sustainable soil resource management across North America.

Technical Abstract: Interpretable indicators of soil hydraulic function are desired by farmers, scientists, and other stakeholders in soil health. Determining which soil health indicators to use when measuring changes in soil hydraulic function has been difficult because of measurement disconformity, spatial and temporal variability, observations on recently established treatments, and the impact of site characteristics on comparison between management practices. The North American Project to Evaluate Soil Health Measurements includes 124 sites uniformly sampled across soil health management practices in North America in 2019. Our goal was to compare and recommend soil health indicators of soil hydraulic function. We assessed 1) the relationship of each indicator to a suite of soil inherent properties and climate variables, 2) the response of each indicator to soil health management practices, 3) the effect that soil inherent properties and climatic variables had on the response of indicators to management practices, and 4) the relationship among the responses of the indicators to soil health management practices. Of the measured indicators, field capacity measured on intact cores (FCINTACT) was the best measure of soil hydraulic function, because it responded to management, represents a direct measure of soil hydraulic function, is proximal to stakeholder values, and its response to management was not significantly influenced by inherent and climatic variables. Other suitable indicators are bulk density, soil organic C, and aggregate stability, which are not direct measures of soil hydraulic function but do respond to management and may be practical in situations in which measuring FCINTACT is not.